Method and device for cleaning slabs, thin slabs, profiled elements, or similar

ABSTRACT

A method for removing loose scale and other foreign matter from the top and/or bottom face of a cast product with the aid of flowable media which are sprayed onto the cast product by a cleaning device having at least one spraying apparatus that is disposed above the cast product and at least one spraying apparatus that is arranged below the cast product. According to the method, the amount of media and/or the effective width and/or the pressure of the media is/are controlled separately and independently of time for each spraying apparatus.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Divisional Application of U.S. patentapplication Ser. No. 12/083,040, filed Mar. 24, 2009, which is a 371 ofInternational application PCT/EP2006/009108, filed Sep. 20, 2006, whichclaims priority of DE 10 2005 047 936.7, filed Oct. 6, 2005, thepriority of these applications is hereby claimed and these applicationsare incorporated herein by reference.

BACKGROUND OF THE INVENTION

The invention concerns a method for removing loose scale and otherforeign substances from the upper surface and/or lower surface of a castproduct, such as a slab, thin slab, profiled element, or the like, withthe aid of flowable media, which are sprayed onto the cast product bymeans of a cleaning device that consists of at least one sprayarrangement positioned above the cast product and at least one sprayarrangement positioned below the cast product. The invention alsoconcerns a corresponding cleaning device.

WO 2002/070157 A1 discloses a method for descaling strip in a rollingmill with a descaler and with a finishing traln arranged downstream ofthe descaler in the running direction of the strip. In this method,water under descaling pressure acts on the upper and lower surfaces ofthe strip, and the strip is cooled in the finishing train. Duringdescaling, a symmetrical temperature distribution is produced on theupper and lower surfaces of the strip inside the descaler and ismaintained in the same way inside the finishing train. The inventionpertains to a descaling operation in combination with a rolling mill.

EP 1 083 010 A2 discloses an adjusting method for two shieldingelements, in which a metal strip with a strip width, a strip center, andedge regions is conveyed in a direction of conveyance on a roller tablewith a roller table center. The metal strip has a temperature gradientover its width. The edge regions of the metal strip are shielded from acooling medium by shielding elements. In this regard, the shieldingelements are adjusted in such a way that the temperature gradientdownstream of the shielding elements with respect to the direction ofstrip conveyance approaches a set temperature gradient. To this end, theshielding elements are adjusted asymmetrically with respect to thecenter of the roller table. This invention describes a method forcontrolling the spray width, which necessitates the use of shieldingelements.

DE 32 30 866 C2 describes a device for a cooling steel sheet panelimmediately after hot rolling. The device is constructed with ahorizontal rolling table for the steel sheet panel; with a plurality ofspray pipes, which extend in the width direction of the steel sheetpanel and are arranged above and below the steel sheet panel atpredetermined intervals in the longitudinal direction of the steel sheetpanel, and each of which has a length that is essentially equal to thewidth of the steel sheet panel; with several nozzles for sprayingcooling water onto the steel sheet panel; and with shielding elements,which are arranged in the region of the two lateral edges of the steelsheet panel for interrupting the jets of cooling water and whose basesare downwardly slanted away from the center of the steel sheet panel. Ashifting device is used to move the shielding elements towards eachother and away from each other in the width direction of the steel sheetpanel lying on the roller table. The shifting device has:

-   -   two stationary guide frames, which are arranged essentially        horizontally above the roller table in such a way that they        intersect the vertical center plane of the roller table;    -   two support frames, which are arranged essentially horizontally        above both sides of the roller table parallel to its center        plane and whose two ends are slidably supported in the guide        frames, such that the shielding element arranged in the area of        one of the lateral edges of the steel sheet panel lying on the        roller table is mounted on one of the two support frames, and        the other shielding element arranged in the area of the other        lateral edge of the stool shoot panel mounted en the other        support frame, and    -   a drive for moving the two support frames, together with the two        shielding elements, towards each other and away from each other        by the same distances in the width direction of the steel sheet        panel lying on the roller table.

This invention describes a device, in which shielding elements are used,for cooling a steel sheet panel after it has been hot rolled.

EP 0 153 688 B1 discloses a method for cooling hot steel sheet from anupstream hot rolling train. The steel sheet is guided in thelongitudinal direction through pairs of upper and lower rolls arrangedin the direction of conveyance of the steel sheet, and cooling water issupplied to the upper and lower surfaces of the steel sheet by nozzleson several cooling units arranged in the same longitudinal direction.Each cooling unit is arranged between adjacent pairs of upper and lowerrollers. The method consists in determining the temperature distributionin the steel sheet before the start of cooling; setting the desired meancooling rate; determining the distance from the edge of the sheet alongwhich the supply of cooling water at least to the underside of the steelsheet is to be interrupted on the basis of the temperature distribution,so that the temperature of the inner edge section of the steel sheet iskept above the temperature of the middle section in order to ensure thatthe Ar₃ transformation in the inner edge section occurs at the same timeas or later than the Ar₃ transformation in the middle section; andshielding a suitable number of nozzles to interrupt the direct supply ofcooling water to the edge section of the steel sheet over the distancedetermined by the preceding process step. This invention applies to thehot steel sheets after hot rolling for the purpose of producing specificsheet characteristics by well-defined cooling.

A cleaning device for removing loose scale from the surface of a slab,especially a thin slab produced in a mini mill, is described, forexample, by DE 101 43 868 A1 and WO 2003/022475 A1. A mini mill of thistype comprises at least a slab casting machine, a slab cutting device, atemperature equalizing furnace, and one or more rolling stands with acoiling installation. A device of this type is improved if a sprayarrangement comprises at least one spray pipe each above and below theslab, with each spray pipe having a plurality of spray nozzles. Thespray arrangement is positioned upstream of the temperature equalizingfurnace, especially a roller hearth furnace. The spray arrangement isconnected to a water supply that has the technologically requiredpressure and a volume flow that is adapted to the number of spraynozzles. Claim 6 states that the water supply pressure to the spraypipes of the spray arrangement is 5-15 bars and preferably less than 10bars.

The existing solutions describe devices with no means of adjustment. Ifone assumes cleaning device with fixed settings of the amount of medium,cleaning width and position, the lack of flexibility results, forexample, in undesired cooling of the thin slab and increased productionrisk. In addition, the upper surface and lower surface experiencedifferent amounts of cooling. With the same amount of medium and thesame medium pressure, the upper surface of the thin slab is morestrongly cooled than the lower surface due to the longer exposure time.The head of the thin slab then tends to rise. This makes the passage ofthe thin slab through the downstream installations more difficult.

When the head of the thin slab strikes something in the downstreaminstallations, a conveyance interruption can occur. This makes itnecessary to shut down the casting installation.

The outer edges of the thin slab are more strongly cooled than themiddle region. In addition, this effect is also dependent on the currentslab width. The causes are:

The medium applied in the middle of the thin slab flows towards theouter edges; therefore, the amount of medium and the cooling effect aregreater at the edges. The cleaning medium reaches the thin slab not onlyfrom above but also, depending on the design, from the outside.

There is the danger of cooling the slab edges too strongly.

The cooling of the thin slab depends on the casting speed. At lowercasting speeds, the cooling is more intense than at higher castingspeeds when the same of medium is applied. The casting speed of acasting plant is typically varied according the production conditions,including the production conditions within a casting sequence. At theend of a casting sequence, the last length of thin slab is ordinarilyseparated and lies on the roller table. If the cleaning device is used,this last section of thin slab cools so strongly that any possibledownstream cutting operations for reducing the size of the last sectionof thin slab must cut a material that is much colder and thus stronger.

If any interruption occurs in the casting plant that makes it impossibleto continue moving the thin slab out of the plant, the thin slab must becut into lengths to allow it to be removed. In the vicinity of thecleaning device, the presence of the cleaning device makes it difficultfor personnel to reach the thin slab. In this regard, quick access tothe thin slab is necessary to prevent the hot thin slab, which is nolonger being conveyed, from overheating and thus damaging parts of theplant.

When the casting process is started up, the head of the thin slab canstrike the cleaning device, especially if the space between the surfaceof the thin slab and the cleaning device is very tight. An undesiredside effect of the cleaning device is the cooling of the thin slab. Thecooling is greater the longer the medium has contact with the thin slab.

With increasing medium pressure, the danger of medium escaping from thecleaning device increases. If this occurs, foreign substances, such asscale, may be carried back onto the surface of the thin slab.

SUMMARY OF THE INVENTION

The objective of the invention is to improve the previously knowncleaning devices in such a way that the properties of the cast product,such as a slab, thin slab, profiled element or the like, are improved byflexible means of adjustment, specifically, of the cooling medium, andto avoid the disadvantages described above.

In accordance with the invention, this objective is achieved by virtueof the fact that in a method of the type specified in the introductoryclause of claim 1, the amount and/or the effective width and/or thepressure of the flowable media is controlled separately andindependently with respect to time for each spray arrangement.

Further refinements of the method are described in the dependent methodclaims.

The invention also concerns a device for carrying out the method of theinvention. In this device, the spray arrangements and/or the nozzleslocated on the spray arrangements are designed to respond to acontrol/guidance system.

Further refinements of the device are described in the dependent deviceclaims.

The decisive advantage of the method of the invention is thatcontrollable means of adjustment for the amount and/or the effectivewidth and/or the pressure of the flowable media can be used for separatecontrol of the upper and lower medium supply at every point in time.

In this way, loose scale and other foreign substances are removed asearly as possible from the upper and/or lower surface of the castproduct. With several additional devices, the use of the cleaning devicebecomes much more flexible and reliable.

With means for adjusting the effective width of the cleaning device tothe width of the cast product, excessive cooling of the edges of thecast product is avoided. Depending on the design, the cleaning devicecan also follow a casting width change of the current cast product. Thewidth adjustment can be made by a switching device and/or by manualdevices for shutting down a definite number of medium supply lines.

With means for adjusting the amount of medium and/or the effective widthand/or the medium pressure, the amount of medium can be varied accordingto the casting speed. This makes it possible to control the coolingindependently of the casting speed and the cast material.

With means for completely stopping the supply of medium to the cleaningdevice, the supply of medium can be completely shut off, e.g., at theend of casting.

With means for partly or completely removing the cleaning device fromthe casting line, access to the cast product is greatly improved. Forexample, the cleaning device can be laterally removed from the castingline, or the parts installed above the thin slab can be lifted off witha lifting device.

The means of the preceding point are improved if the removal is effectedwith a remotely controlled drive. These means are also improved iftime-consuming disconnection of supply lines is eliminated by flexiblemedium connections or self-closing medium couplings.

With several measures used individually or together, the residence timeof the flowable medium on the surface of the cast product can beshortened. Depending on requirements, the devices can be used upstreamand/or downstream of the cleaning device:

-   -   An additional spraying off of the cast product with flowable        medium that can be adjusted in its amount and/or effective width        and/or pressure, for example, low-pressure water, prevents the        flow of medium in the casting direction or in the direction        opposite the casting direction.    -   An additional blowing off of the cast product with air helps the        medium flow off to the sides.    -   Collecting channels can be used to remove the medium from the        upper surface of the cast product.

The cleaning device is enclosed in a housing—if this is possible from adesign standpoint. The streams of medium are possibly collected withcollecting channels and drained away to the sides in a well-defined way.To assist the draining off of the medium, flushing with medium can beprovided in these collecting channels.

All of the means of adjustment described above can be activateddifferently. In this regard, depending on the adjustment parameter, theactivation can be accomplished from one or more places that are possiblyblocked relative to each other:

-   -   Manually from the appropriate control platforms of the casting        installation.    -   Manually from an on-site control console.    -   Automatically from a guidance system used expressly for the        cleaning of the cast product.    -   When there is connection with a higher-order guidance system,        adjustments that depend on the production process can be partly        or completely automated or can be provided in advance to the        operating personnel as proposed values.

The invention allows more flexible use and more reliable productionoperation of a cleaning device and a better cleaning effect andreduction of undesired side effects. In addition, the adjustments of thecleaning device can be adapted with automation to the different castingparameters and casting production steps.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of the disclosure. For a better understanding of the invention, itsoperating advantages, specific objects attained by its use, referenceshould be had to the drawings and descriptive matter in which there areillustrated and described preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWING

In the drawing:

FIG. 1 shows a schematic side view of a thin slab installation.

FIG. 2 shows a side view of a cleaning device of the invention withinthe casting line.

FIG. 3 a shows a side view of the cleaning device of the invention,opened by swinging it up.

FIG. 3 b shows a side view of the cleaning device of the inventionoutside the casting line (laterally displaceable design).

FIG. 4 shows a possible arrangement of the spray arrangements in detail.

FIG. 5 shows an arrangement of spray nozzles in detail (nozzles that canbe turned off are drawn with a different type of line).

FIG. 6 shows a system for longitudinal spraying in detail.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a casting plant. The cast product 3 emerging from a castinginstallation 2 is turned by rollers 4 from a vertical to a horizontalposition. The cast product 3 then passes through a cleaning device 5. Inthe cleaning device 5, scale and other foreign substances are removedfrom the upper and/or lower surface of the cast product 3. To allowfurther processing, for example, in a rolling mill 6, the cast product 3is heated in a heating installation 7. The cleaning device 5 is providedwith at least one spray arrangement 8 positioned above the cast product3 and at least one spray arrangement 9 positioned below the cast product3. A cutting device 28 (e.g., a shear) is installed upstream ordownstream of the cleaning device 5.

An example of a cleaning device 5 is shown in greater detail in FIG. 2.The cleaning device 5 installed/mounted on a foundation 10 consists of atop frame 11 and a bottom frame 12. Spray arrangements 8, 9 are mountedon the top frame 11 and the bottom frame 12. The spray arrangements 8, 9are furnished with a plurality of nozzles 13. The spray arrangements 8,9 are supplied with a flowable medium via lines 14, 15. Deflectors 17,18 are mounted below the casting line 16 to help carry away the flowablemedium.

The top frame 11 is supported in such a way that it can swivel up anddown. As shown in FIG. 3 a, it can be swung out of the casting line 16by means of a hydraulic cylinder 21.

Alternatively, the cleaning device 5 is displaceably mounted on rails19, 20 and can be moved out of the casting line 16 by means of ahydraulic cylinder 21. FIG. 3 b shows this alternative cleaning device 5outside the casting line 16. In the embodiment illustrated here, the topframe 11 and the bottom frame 12 are designed with a U shape. Tostabilize the cleaning device 5, the free ends 22, 23 are set by meansof pins 24, 25 in corresponding bores of an abutment 28.

FIG. 4 shows details of a system with two spray arrangements 8positioned above the cast product 3 and one spray arrangement 9positioned below the cast product 3. The nozzles 13 are oriented in sucha way that they spray the cast product 3 with the flowable medium in thecasting direction 16 or opposite the casting direction 16. To this end,the nozzles 13 can be oriented, for example, at a fixed angle.

The two spray arrangements 8 positioned above the cast product areoriented in opposite directions. This reduces the emergence of theflowable medium in the casting direction and in the direction oppositethe casting direction.

FIG. 5 shows details of an arrangement of nozzles 13. The spray cones 29are configured in such a way that they overlap. Therefore, the flowablemedium strikes the entire surface of the cast product 3. Design measurescan be taken to allow a well-defined number of outwardly arrangednozzles to be turned off.

FIG. 6 shows a number of nozzles 13, which are arranged for analternative system of longitudinal spraying.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the inventive principles, it will beunderstood that the invention may be embodied otherwise withoutdeparting from such principles.

We claim:
 1. A method for removing loose scale and other foreignsubstances from the upper surface and/or lower surface of a castproduct, such as a slab, thin slab, profiled element, or the like, withthe aid of flowable media, which are sprayed onto the cast product bymeans of a cleaning device that consists of at least one sprayarrangement positioned above the cast product and at least one sprayarrangement positioned below the cast product, where a heatinginstallation and a rolling mill are installed downstream of the cleaningdevice, wherein the amount of medium and/or the effective width and/orthe pressure of the medium is controlled separately and independentlywith respect to time for each spray arrangement.
 2. A method inaccordance with claim 1, wherein the cleaning device is operated with atleast one static spray arrangement.
 3. A method in accordance with claim1, wherein the cleaning device is operated with at least one movablespray arrangement.
 4. A method in accordance with claim 1, wherein thecleaning device is operated in the low-pressure range.
 5. A method inaccordance with claim 1, wherein the cleaning device is operated in thehigh-pressure range.
 6. A method in accordance with claim 1, wherein themeans of adjusting the spray arrangements are operated independently ofthe casting speed and/or the cast material.
 7. A method in accordancewith claim 1, wherein the supply of medium can be completely stopped. 8.A method in accordance with claim 1, wherein the cleaning device isenclosed in a housing.
 9. A method in accordance with claim 1, whereinthe cleaning device can be moved laterally completely out of the castingline.
 10. A method in accordance with claim 1, wherein the part of thecleaning device located above the cast product is removed.
 11. A methodin accordance with claim 9, wherein the cleaning device is moved out orlifted out with a remotely controlled drive.
 12. A method in accordancewith claim 1, wherein the cleaning device is connected to supply linesby medium connections that are flexible.
 13. A method in accordance withclaim 1, wherein the cleaning device is connected to supply lines byself-closing medium couplings.
 14. A method in accordance with claim 1,wherein an additional spraying off of the cast product with medium thatcan be adjusted in its amount and/or pressure prevents the flow ofmedium in the casting direction or in the direction opposite the castingdirection.
 15. A method in accordance with claim 1, wherein at least anadditional blowing off of the cast product with air helps the mediumflow off to the sides.
 16. A method in accordance with claim 1, whereincollecting channels are used to remove the medium from the upper surfaceof the cast product.
 17. A method in accordance with claim 14, whereinthe additional devices off the cast product with medium, device forblowing off the cast product with air, medium collecting device) areused upstream and/or downstream of the cleaning device.
 18. A method inaccordance with claim 1, wherein the control system of the cleaningdevice is operated by connection with a higher-order guidance system.19. A method in accordance with claim 1, wherein the adjustments of thecleaning device that depend on the production process are partly orcompletely automated.
 20. A method in accordance with claim 1, whereinthe adjustments of the cleaning device that depend on the productionprocess are provided in advance to the operating personnel as proposedvalues.